Share

cover art for Finding the trees to survive the future, with Kevin Martin head of tree collections at RBG Kew

HortWeek Podcast

Finding the trees to survive the future, with Kevin Martin head of tree collections at RBG Kew

Season 5, Ep. 13

In the hot summer of 2022, RBG Kew lost more than 400 trees. By July 2024, Kew announced that it believed over 50% of its trees could be at risk by 2090 due to environmental changes due to climate change.


This week's guest is Kevin Martin, head of tree collections at Royal Botanic Gardens Kew and he joined the HortWeek Podcast to relate the research Kew has done that led it to such a stark conclusion.


"What we started to look at first was mortality data, but we soon realized that that's a really unstable data set. can't always know why a tree or a plant has died in the landscape. It's not always due to environmental factors.


"We then started looking at climate modeling...and using species observation data to start building a better picture of the impact of climate change on the living landscape here at Kew.


Perhaps surprisingly, the focus was not on identifying vulnerable species, but "the provenance of the seed".


Kew studied its own environment, located as it is in "an urban heat island" on the edge of Greater London with relatively thin and poor soil, "so the effect of climate change is always exaggerated". 


To understand the plants that suited this environment, they found themselves in the Romanian steppe which proved a good match.


His next trip will take him to Georgia to find more species that might thrive at Kew.


Rather than building more and more glasshouses to create the right condition for plant collections, with their huge energy bills, botanic gardens must play to their strengths and grow the plants that fit their ecosystem and climate profile.


"And the native, the English native one is a really interesting question. 


"You've got Quercus robur, they all have a large distribution range. So we're now looking at their dryest range to understand how those trees have adapted...they will grow right up to the edge of Azerbaijan, right on the dryest edge of their range. So we're selecting seed from those areas to bring them back to Kew to understand how they've adapted."


And the change needs to translate to all green spaces and gardens, large and public as well as domestic and small.


"A lot of the plants that we all go to the garden centre to put in our own private gardens, those trees have been selected for us realistically by the Victorians. A lot of those plants are available in commercial nurseries, they're all from the original plant collectors from the Victorian era especially, and they're the same cloned material that's just passed round.


"So it's really not just changing the planting palette within Botanic Gardens...This is a change of planting palette... and that does need support and investment in further research from government in order to support the commercial nurseries as well.


"I do think it's going to be the biggest shift we've seen since the start of the organisation back in the 1840s". 

More episodes

View all episodes

  • 12. Fighting for our right to roam, with Kate Ashbrook of Open Spaces Society

    24:26||Season 5, Ep. 12
    Kate Ashbrook is an author and has been the general secretary of the Open Spaces Society for 40 years and counting, but she is first and foremost, a campaigner.On this week's HortWeek Podcast she recounts some of the best changes she has seen during her tenure - "the greater awareness of the importance of open spaces for the public and the greater awareness among the public of the importance to them of open spaces, paths, getting out there, enjoying the countryside and green spaces in towns.And the worst... "After 40 years, open spaces, commons and paths are still very much under threat. We haven't made that step change, which means that governments, local authorities recognise that actually open spaces and paths are so important that we need to invest in them fully. They may say they're important, but they don't actually put the money and the resources in."Current focuses include closing the "green space gap" in the current National Planning Policy Framework:"We don't see in the consultation, governments giving prime importance to green spaces. We think they should be at the core of all planning policies, thinking about the wider public and what people need and then framing the development around that... we shall be making suggestions of how government can give greater priority to green spaces." Rachael and Kate also discuss biodiversity net gain and how that interacts with the society's goals and wider issues.With a new Government in place she talks about her hopes for policy change and support for offering greater access to land and protection of common land that has always been at the core of the OSS's mission.She outlines the Open Spaces Society's long history - from its foundation in 1965 - which is bound up with the creation of the National Trust. And she recounts some of her own, fascinating career path and what motivates her."I really want to help people to campaign. 50 years ago, I got into campaigning because I met a wonderful person called Sylvia Sayre on Dartmoor and she was 50 years [older than me] and ]encouraged me and helped me and gave me opportunities. And I am thinking, well, I'm now the age that she was when I met her and it's my turn to kind of pass the baton to the younger generation. And I'm out there looking for people to talk to and to learn from and to help."Find out more at https://www.oss.org.uk/
  • 11. The End of Peat: Episode 4 - A whole new take on horticulture

    36:43||Season 5, Ep. 11
    HortWeek presents The End of Peat, a new four-part podcast series that will hear from leading horticulturists and garden retailers as they navigate a transition to peat-free that is piling pressure on a sector facing stresses on all sides.Over the four episodes, Christina Taylor explores the story of the UK peat ban, how the horticulture industry is facing up to the challenge, and how it might shape the future of the sector.In Episode 4 we hear from growers who have successfully made the leap to peat-free. Christina asks whether growers are ready for legislation and industry figures voice how it could work without destroying the horticulture industry in the process.Written, produced and presented by Christina Taylor
  • 10. The End of Peat: Episode 3 - The cost of trial and error

    29:59||Season 5, Ep. 10
    HortWeek presents The End of Peat, a new four-part podcast series that will hear from leading horticulturists and garden retailers as they navigate a transition to peat-free that is piling pressure on a sector facing stresses on all sides.Over the four episodes, Christina Taylor explores the story of the UK peat ban, how the horticulture industry is facing up to the challenge, and how it might shape the future of the sector.In Episode 3: The cost of trial and error, Christina explores the two particular challenges faced by UK horticultural growers.Where peat-free might cause an amateur gardener to lose a batch of lettuce seedlings, professional growers face the loss of entire crops as many attempt to trial new, and quite alien, growing media mixes.Professional growers tell us their stories of trial and error, what they have learned in the process and discuss the fears that some plants and specialist nurseries will be lost to the UK for good.Series writer, producer and presenter is Christina Taylor
  • 9. End of Peat: Episode 2 - From Multipurpose to pick 'n' mix

    38:38||Season 5, Ep. 9
    HortWeek presents The End of Peat, a new four-part podcast series that will hear from leading horticulturists and garden retailers as they navigate a transition to peat-free that is piling pressure on a sector facing stresses on all sides.Peat is one of the most popular and reliable types of growing media for plants, but peatlands are also a valuable store for carbon and as the UK Government tries to meet net zero targets, a peat ban is on the agenda.Over the four episodes, Christina Taylor explores the story of the UK peat ban, how the horticulture industry is facing up to the challenge, and how it might shape the future of the sector.Christina asks:Do we need a peat ban?Why is the transition to peat-free causing so much division and proving so difficult?And as the sector navigates the numerous challenges, she asks what is needed for the sector to survive, if and when peat ban legislation actually comes into effect.In Episode 2: From multi-purpose to pick 'n' mix, Christina explores the two particular challenges faced by garden centres. The first is the transition from selling peat-based compost to peat-free mixes. Challenges here include the variable quality of peat-free compost mixes, fears over supply of new ingredients, the higher price of these mixes and how they can help educate amateur gardeners learn to grow their plants. Many have found difficulties in germinating seeds prompting fears that thousands of customers, particularly those trying to Grow-Your-Own fruit and veg, may give up, costing garden centres valuable customers in the process.We hear about the initiatives from thought leaders in the industry on how these challenges can and should be addressed.The second challenge relates to the sourcing of plants that have been grown in peat-free compost. This is where the interests of retailers intersect with the growers as peat-free adds to cost pressures. Ways to grow so-called tricky plants continue to be elusive prompting fears that we may lose the ability to buy whole categories of plants in the UK.
  • 8. The End of Peat: Episode 1 - Do we need a peat ban?

    32:10||Season 5, Ep. 8
    HortWeek presents The End of Peat, a new four-part podcast series that will hear from leading horticulturists and garden retailers as they navigate a transition to peat-free that is piling pressure on a sector facing stresses on all sides.Peat is one of the most popular and reliable types of growing media for plants, but peatlands are also a valuable store for carbon and as the UK Government tries to meet net zero targets, a peat ban is on the agenda.Over the four episodes, Christina Taylor explores the story of the UK peat ban, how the horticulture industry is facing up to the challenge, and how it might shape the future of the sector.Christina asks:Do we need a peat ban?Why is the transition to peat-free causing so much division and proving so difficult?And as the sector navigates the numerous challenges, she asks what is needed for the sector to survive, if and when peat ban legislation actually comes into effect.In Episode 1: Do we need a peat ban? Christina unearths why a peat ban is being proposed and outlines some of the arguments for and against. It examines the history of peat use in the UK, the properties of peat and peat-free growing media, and begins to unearth why the topic has so bitterly divided the horticulture industry. The End of Peat was written, produced and presented by HortWeek digital content manager Christina Taylor
  • 7. Inspiration for garden centre trees with Kernock Park Plants' nurseryman and award-winning writer, Bob Askew

    27:12||Season 5, Ep. 7
    Bob Askew was Garden Media Guild award winner a year ago for his new writer work for Hortweek. He works for Kernock Park Plants as production director and was previously at Darby Nursery Stock and Brinkmans.Here he names his top three tree genera for gardens, three underused tree genera and top five skinny trees for small gardens.He believes the reliance of nurseries and garden centres on too few ornamental tree cultivars is a bad thing and is critical of overuse of Betula utilis var. jacquemontii and Crataegus Paul's Scarlet, and offers alternatives to them.Askew also names three awful crab apple cultivars and five brilliant ones for gardens, as well as five brilliant but below-the-radar flowering cherries.He delves into the pros and cons of growing trees in solid pots, versus airpots, or slotted pots.
  • 6. Keeping it local for houseplants with Imogen Bell of YPHA and Thomson's Garden C

    19:35||Season 5, Ep. 6
    This week the HortWeek Podcast meets Imogen Bell, supervisor at Thomson's Garden Centre and a YPHA Southeast regional coordinatorIn her article for HortWeek 'Despite CITES, not all doom and gloom for houseplant sales' Imogen reflects on how the reinterpretation of CITES "meant practically a third of my stock became unavailable overnight". One of the "Brexit benefits" often quoted was the possibility that more friction across the borders would encourage clients to buy British and boost British-grown plants. As tightening border controls cause unprecedented chaos at BCPs Imogen might be feeling a degree of relief that she took the decision to switch to British houseplant nurseries months ago."Cacti, carnivorous plants, the majority of orchids... it's almost impossible to import, which is obviously quite a large part of most houseplant departments."Luckily, I was already having looking into UK growers after Brexit - just in case anything got super difficult to import. And at the same time a lot of UK nurseries then opened up to garden centres - Oppenman's plants, Double H, Hills Brothers all opened up to garden centres about the same time.I was already ordering from them so I just got to order in much higher volume.The only plants she's struggled with are more unusual orchids, she says, but initiatives such as Horti House which allows nurseries to trade as one unit is helping."You get some great nurseries in there like Dibley's who do Streptocarpus and Begonia.. and where before you would have to order either half a trolley or a whole trolley, you can now just order by the tray which means you can get a good range of more unusual things without having to kind of put all your eggs in one basket with a specific supplier."She talks about the challenge of competing with supermarkets with their economies of scale, "but on the other hand, I think if you look at any supermarket at their house plant department, it is all half-dead... where garden centers and other plant shops really stand out is the level of knowledge and customer service they can offer".At Thomson's she has added labels showing the air miles for plants on sale: "I'd like to introduce UK suppliers and just extend that so you can say this orchid or Monstera or whatever has come from 40 miles away and it's come from this nursery and it's a family -run business. I think it just adds to the value of the plant to be able to give it that origin."It surprises her that, given the huge rise in popularity of houseplants in recent years, many garden centres fail to put on a good display.New trends she is seeing include Marimo moss balls. They grow like a couple of millimetres a year. But for some reason they were flying off the shelves." The appeal for many customers she says, are plants that "thrive off neglect".On peat-free, Imogen says customers are asking for it and garden centres are moving in that direction, ban or no ban. "Horti House is peat-free and again out of necessity I guess the other ones will come into line" she says.On peat-free composts, she says: "I've noticed more and more people are mixing their own soils. So instead of just getting a packet off the shelf, they're buying a base and then they're buying perlite or coir or coco husk and then blending it for the specific plant".And will the houseplant boom continue?"I'm not sure we'll quite get the sky high sales we had during the lockdowns...They've plateaued since, but the interest is consistent. I don't think house plants will go away."
  • 5. What it is like exhibiting at Chelsea Flower Show? with Sparsholt College students

    13:18||Season 5, Ep. 5
    HortWeek is delighted to present the Cultivate Your Future podcast, in partnership with the Colegrave Seabrook Foundation and sponsor Westland Horticulture.At a time when horticulture needs to encourage a new wave of young people to come into the industry, this podcast is designed to highlight the multiple and varied career opportunities available.Hear from people who have found their way into their chosen career through different paths, what their job involves and what it means to them.In this episode Neville Stein catches up with students from Sparsholt College to discuss their recent experience of exhibiting at RHS Chelsea Flower Show and how they felt about it.As the Colegave Seabrook Foundation supports students studying horticulture, we were very proud to be sponsors of their exhibit and are thrilled at their success.